Currently, a wide range of portable consumer electronics that are not dedicated to photographic uses are equipped with cameras. These portable consumer electronics may include, for example, smart phones, laptops, notebooks, tablet computers, and personal digital media players. These portable consumer electronics are often constrained in both x-y area and z-height or thickness such that the camera included therein must be designed to meet the sizing constraints while providing adequate camera quality.
The optical total track length (TTL) is one of the most important factors determining the z-height of a camera included in portable consumer electronics. Since the optical TTL dictates the distance between the camera lens and the image sensor, in order to properly integrate the camera into a thin portable consumer electronics device, it is necessary to reduce the TTL without affecting the imaging performance of the camera.
Another important factor in determining the z-height of a camera is the Chief Ray Angles (CRA). The CRA is the angle measured from the vertical axis drawn through the center of the lens (i.e., the normal) to the meridional ray that starts at the edge of the object that is being captured in photo and passes through the center of the lens. Many sensors are sensitive to high CRAs (e.g., greater than 20 degrees) such that it is necessary to reduce the high CRAs at larger field heights in order to improve the overall imaging performance of the camera.